This invention relates to fused salt mixtures suitable for use as low temperature battery electrolytes and to a method for their preparation. More particularly, this invention concerns itself with AlCl.sub.3 /1-Alkyl pyridinium room termperature molten salt mixtures and their use as low temperature primary or secondary battery electrolytes.
The recent interest in developing lightweight power sources for airborne military and emergency applications has generated a considerable materials research effort in an attempt to find new and more efficient component parts for electrochemical power supplies. One particular area of concern has been the use of fused salt mixtures as electrolytes. Generally, such mixtures are solid at room temperature and require the use of a heat activating means in order to melt the electrolytes and activate the battery. Unfortunately, certain electro-chemical couples are relatively unstable at these high temperatures, and this limits or eliminates their use in a battery system.
With this invention, however, it has been found that AlCl.sub.3 /1-Alkyl pyridinium chloride room temperature molten salts are especially useful as an electrolyte for primary and secondary batteries. These salt mixtures are fluid at ambient temperature and their low liquidus temperature, light insensitivity, and electrochemical window are characteristics that render these materials especially useful as low temperature battery electrolytes. This invention provides a molten salt medium that retains the electrochemical properties of present high temperature molten salt systems but without the use to provide and maintain high operating temperatures. It allows for the need of various anode-cathode couples showing excellent primary and secondary battery potentials which cannot be employed in high temperature molten salt systems.